量子化学从头计算法计算石墨微晶中碳原子的净电荷

Determination of net charge of carbon atoms in graphite crystallite by ab initio calculation method

采用从头计算法在RHF/STO-3G水平上对石墨微晶中不同位置碳原子的净电荷进行量化计算;研究碳原子的净电荷与炭材料的微观结构变化规律;根据石墨的结构与成键特征,将石墨表面的碳原子分为边缘碳原子与基平面碳原子。研究结果表明:在单碳层及含多层碳的石墨微晶中,不同位置碳原子的净电荷数差别较大;基平面碳原子的电子云密度较小,均带部分正电荷;部分边缘碳原子的电子云密度较大,净电荷为负。随着平行于碳层的微晶尺寸La及垂直于碳层的微晶尺寸Lc的增大,边缘碳原子中电子云密度最大的碳原子所带的负电荷增加。

The net charge of carbon atoms in graphite crystallite was determined by ab initio calculation employing RHF/STO-3G basis, and the relationship between net charge of carbon atoms and structure of carbon anodes was investigated. According to the characteristics of bond and the structure of graphite crystallites, carbon atoms on the surface of the crystallites were divided into basal plane carbon atoms and edge carbon atoms. The results show that in the single graphene layer and graphite crystallite, the carbon atoms at different sites show obvious difference in net charge. All the basal plane carbon atoms on the surface of crystallite have lower electron density and show positive net charge, while part of the edge carbon atoms have higher electron density and show negative net charge. As graphite crystallite sizes are parallel to the layers La and perpendicular to the layers Lc rise, the maximum negative charge of edge carbon atoms increases.